Animals may evolve a preference for a varied diet in order to get the many nutrients they need. A test of this on mice would be whether their preference for different grains is negatively autocorrelated, i.e. they are less likely to choose a food if they have eaten more of it recently.
Variety is perceived mainly through taste, so the mechanism via which the preference for a varied diet probably operates is that consuming a substance repeatedly makes its taste less pleasant for the next meal. Spices and other flavourings can make the same food seem different, so may interfere with variety-seeking, essentially by deceiving the taste. A test of this on mice would flavour the same grain differently and check whether this attenuates the negative autocorrelation of consumption, both when other grains are available and when not.
If seasonings reduce variety-seeking, then access to spices may lead people to consume a more monotonous diet, which may be less healthy. A test of this hypothesis is whether increased access to flavourings leads to more obesity, especially among those constrained to eat similar foods over time. The constraint may be poverty (only a few cheap foods are affordable) or physical access (living in a remote, unpopulated area).
A preference for variety explains why monotonous diets, such as Atkins, may help lose weight: eating similar food repeatedly gets boring, so the dieter eats less.
Overconsumption of salt is a significant public health problem. People are reluctant to reduce the saltiness of their food, because it would taste bland. Eventually, preferences adjust so that a diet without added salt tastes normal and salted foods are perceived as too salty. The only question is how quickly tastes adapt.
My experience of stopping adding any salt to my food was that the bland taste lasted less than 3 days, after which I had fully adjusted to the new reduced level of saltiness. An easier way to adapt may be to gradually reduce the amount of added salt, as opposed to suddenly cutting off all of it, as I did. In that case, there may be no perceived taste difference, especially if the reduced salt is accompanied with increased amounts of other seasoning, like pepper. Given the smallness of the adjustment cost and the health benefit of cutting salt consumption, doing it is a clear and easy win.
Strangely enough, fancy office chairs are often upholstered in leather or other non-breathable material. After an hour or so, sitting in them gets uncomfortable because the moisture does not evaporate from the skin that is separated from the chair only by some cloth. However, people usually sit in office chairs for hours at a time, and I doubt that the chairs are designed to deliberately provide some discomfort to encourage users to occasionally stand up for health reasons. Especially in a hot climate when the air conditioning may break down or just be too weak, a breathable chair would make much more sense. Making a mesh chair is simple: stretch a breathable fabric on the chair frame. The small holes in the fabric let moisture evaporate from the surface. A mesh chair is probably cheaper to manufacture than a leather-upholstered one.
A reason for using leather may be to signal wealth by using a material associated with expensiveness.
Modern synthetic meshes are as durable as leather for practical purposes, because sitting in a chair is not a high-wear use.
Adjustable-length metal crutches click with each ground contact and lifting, which some people find annoying. The reason for the clicks is that the push button used to adjust the length of the crutch is not snug in its hole, but pushes against the top of its hole when the crutch is pressed against the ground and against the bottom of the hole when the crutch is lifted.
The push button length adjustment system consists of two pipes inside each other, with holes in the outer pipe and a spring-loaded button on the inner one. Pushing the button in allows the pipes to slide relative to each other. When the button is released and pops out into a hole, it locks the pipes together. Similar push button systems are used to adjust the handle length of rolling luggage and the weight stacks of gym equipment.
To silence the clicks, the button should push against the same side of the hole at all times, which can be achieved by adding one spring. The spring should pull the inner pipe of the adjustable part of the crutch in the direction of shortening the crutch, i.e. the same direction as ground contact. Then the button always stays in contact with the same side of its hole instead of alternately hitting the two opposing sides. The reason the spring should pull in the same direction as ground contact is that the upward force on the adjustable inner pipe when the crutch bears the weight of the user is much greater than the downward force of the weight of the inner pipe when the crutch is lifted. Thus it is easier to overcome the downward force using a spring.
A homemade version of the spring is to tie a rubber band under tension to above and below the adjustment button. A bungee cord or bicycle inner tube would work as well.
The length adjustment of the crutch with a spring would be similar to that of an office chair – automatic in one direction, but requiring force in the other. When the button is pushed, the crutch shortens automatically by one hole. To lengthen the crutch, one has to push the button in and then pull the crutch in two opposing directions.
Testing illegal drugs for the active ingredient differs from testing for poisonous adulterants. Both tests have opposite effects on drug use before and after buying. After the pill has been purchased, testing reduces use, because sometimes the drug fails the test, whether correctly or not, and is discarded. Before purchase, the option to test for and avoid adulterated or inactive drugs reduces the buyer’s risk, thus increases use.
In the longer term, testing benefits the dealers of purer, more predictable and less toxic drugs, putting some suppliers of fakes out of business. Pill predictability reduces overdoses – a health effect similar to lower toxicity. If old drugs can be tested, but new ones not, then buyers experiment less and the incentive to invent new narcotics decreases.
The avoidance of poisonous adulterants is good for public health, but purer pills not necessarily so. Inactive drugs undermine consumer confidence in the illegal market, reducing use, prices and casual purchases. Trust then requires a long-running relationship with the seller, which has multiple benefits. It motivates dealers to care about the health of their loyal customers, simplifies policing and gives researchers and social workers better long-term access to the at-risk population.
One claimed benefit of party drugs is that they reduce anxiety, increase the user’s confidence and social interaction, thus improving mental health. Evidence from psychiatric medicines suggests that many such benefits are due to the placebo effect. Users are quite inaccurate in estimating the purity of ingested drugs, and factors like price and place of purchase strongly influence their perception of purity. The price per pure gram is negatively related to purity in some markets, further supporting the placebo interpretation. If inactive pills boost confidence similarly to illegal drugs, then there is a clear case for flooding the market with harmless placebos. The availability of pill tests for the active ingredient reduces this opportunity to make the illegal market inefficient. Tests for toxic adulterants, however, actually favour harmless placebos.
Shoes are typically of thinner material in the toes than around the ankle, but human toes are more cold-sensitive than ankles, because toes have a greater ratio of surface area to volume (thus greater heat loss) and are further from the core of the body, so get less warm blood supply. Similarly, pants are usually thicker on the butt (due to pockets) or the upper end in general (suit pants lined to the knee), in spite of the legs requiring more warming than the pelvic region. Suit jackets are open on the chest, but overlap on the belly, which needs less extra insulation. The same suboptimal distribution of warmth characterises various V-necked upper body clothes. Jackets are also thicker on the front than the back, despite most people’s backs being more cold-sensitive than bellies.
This impractical design can be explained for men’s jackets by the desire to improve the wearer’s looks with the visual illusion of broad shoulders created by the V-shape of the front of the jacket. I have written about this in more detail: https://sanderheinsalu.com/ajaveeb/?p=885
For other clothes and shoes, there seems to be no reason for the suboptimal distribution of thickness, which would be easy to fix in the manufacturing process. The extra layers of cloth added by pockets could be balanced by using thinner cloth to make the pocket area of the pants. The pocket pouches on jeans for example are usually of thin cloth, which is a step in the right direction. However, the surface of the pants covering the pockets is usually of the same cloth as the legs. Lining could easily be added to trouser legs to make these as thick as the upper part, compensating for the extra layer of cloth by manufacturing the trousers out of thinner material overall. Similarly, adding a layer to the back of a jacket is easy.
The only difficult part to compensate in the impractical thickness distribution of clothing is the thin chest cover (relative to belly and back) of a V-neck jacket, but this difficulty only arises from the desire to preserve the look of a V-neck. A similar visual illusion of broad shoulders could be created by painting a V-shaped pattern on the garment.
A different impractical aspect of shoe design that can be explained by fashion is the pointy toes. The tapering tips create an optical illusion that makes the feet seem longer, which does not necessarily improve the wearer’s looks. However, fashion is frequently ugly, as evidenced by the web search results to the phrase: „it’s called fashion, look it up”.
Somewhat counterintuitively, moving a part of the body a greater distance may be easier in some cases. For example, lying on your back and lifting straight legs off the floor, the muscles work harder when the legs are close to the floor than when they are close to vertical. Leg lifts lying on your back are easier when their amplitude is larger (90 degrees as opposed to 45 degrees off the ground).
In many exercises, lifting the limb to an easier position gives the muscles a rest, making the workout less intense (calories burned per unit of time) overall. Examples are biceps curls until the forearm is vertical, straight arm raises all the way overhead, deadlifts to a straight or even backward tilting posture, as opposed to stopping partway through. Slower movement may make an exercise more intense by spending more time in an effortful position, e.g. slow push-ups or squats.
Lifting a longer distance may also make an exercise easier by giving a greater opportunity to swing the limb and use inertia, which is usually bad technique. For example, standing leg lifts to the front take less effort when the leg starts from behind the body and is already moving when passing vertical, compared to starting from holding the leg slightly to the front of the body.
A half-year visit to a US university under a J1 visa requires US health insurance. In the University of Pennsylvania, the website of the International Students’ and Scholars’ Office says that they have pre-selected some health insurance plans. According to their cover description and comparison websites, these plans offer significantly less cover than similarly-priced plans not pre-selected by U Penn. My spreadsheet comparing the health insurance options is public. Possibly I have missed some aspects of insurance that justify the price difference. Another explanation is that the pre-selection was done by people who do not themselves use these insurance plans (because they are not visitors to the US) and have little incentive to make an effort to choose the best plan. A more negative and less likely interpretation is that the insurance company is providing incentives (such as kickbacks) for the selectors at U Penn to direct visitors to expensive low-cover plans that are profitable for the insurer.
Warning: this Christianity- and Christmas-themed post may offend or disgust. The procedure described is unpleasant for the receiver.
Fertilisation of an egg cell requires sperm to reach it, which does not require breaking the hymen. A thin tube, such as a hollow straw or reed, can be inserted through the small opening in the hymen to pump sperm (obtained via male masturbation) into the vagina. The simplest way to pump the sperm is to suck it into the straw with one’s mouth and then blow it out. Another way is with an enema pump (bulb syringe) that can be constructed with primitive technology: a hollow leather ball glued to a reed using resin, tar or bone glue. The seams of the leather ball can be waterproofed with tar. The ball can be made to spring back into shape after squeezing, e.g. by constructing it with wire hoops or springs inside.
Successful fertilisation with the above method likely requires many attempts, because the probability of pregnancy from unprotected sex during the most fertile part of the menstrual cycle is 30%. Sexual activity causes hormonal changes in the female organism that facilitate fertilisation, which a simple reed insertion probably does not, but it may be possible to create similar hormonal changes with an erotic massage.
The above method can be used to arrange a virgin birth in a primitive society. No miracles are required, although a virgin giving birth may be marketed as miraculous.
Modern in vitro fertilisation technology of course expands the range of ways to engineer a virgin birth.
If it is necessary to put cream on a burn frequently, then a band-aid is inconvenient, because it must be pulled off every time. Also, a band-aid may stick to an oozing wound and reopen it every time it is pulled off. If the damaged skin needs covering, for example because the weather requires thick clothes, then one solution is to stick or tie a small cup-shaped object on top of the wound. Tying is preferable, because removing a stuck object again irritates the damaged area. The edges of the cup should be soft, because these press on the skin (so a plastic bottle cap is a bad idea). One soft-edged approximately cup-shaped object is the eyepiece of swimming goggles.
Swimming goggles protecting wound
The eyepiece is nicely attached to adjustable straps for tying it on with neither too much nor too little pressure. The eyepiece may be flipped over to the side to get access to the damaged skin.
Of course, the location of the wound may cause difficulties in tying swimming goggles on top of it, e.g. on the torso. Even on the arm or the leg, the lengthwise movement of the sleeve or pant leg may push the goggles off, because the strap running around the limb does not resist lengthwise movement well. Then adding some bandages may be necessary.
Overnight, the area under the goggles gets sweaty. To avoid this, small air holes may be drilled in the eyepieces, which of course makes the goggles useless for swimming.